Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Income Tax (Textual)
Deferred income tax assets valuation allowance percentage	100.00%	100.00%
Operating loss carryforwards	$ 187,000
Operating loss carryforwards expiration term	The net operating loss carryforwards will start to expire in Fiscal 2022, with the loss from Fiscal 2017 expiring in Fiscal 2037.
Suspended losses became available to offset taxable income			$ 3,000	$ 3,000
Interest on income taxes	$ 6,000	$ 5,000	0
Accrued interest on income tax
Straight Path Spectrum [Member]
Income Tax (Textual)
Operating loss carryforwards	170,000
Straight Path IP Group [Member]
Income Tax (Textual)
Operating loss carryforwards	$ 17,000